Assertion: Purine bases present in DNA are adenine and guanine.
Reason: The base thymine is present in RNA while base uracil is present in DNA.
A. If both assertion and reason are true and reason is the correct explanation of assertion.
B. If both assertion and reason are true but reason is not the correct explanation of assertion.
C. If assertion is true but reason is false.
D. If both assertion and reason are false.